Self-locking boom hoist



April 18, 1933," G, T, RONK 1,904,930

SELF LOCKING BOOM HOIST Filed Sept. 29, 1930 Patented Apr. 18, 1933 renown ranonx, or iftrxnsfrown i maar A f ppnatiqnfmeduseptember 29,1930.: serial N q.' 485,141;

This vinvention relates toj improvements in lowering-the ree'end' oftheboom.

Y vate the boom ;l and to provide inl connection therewith hand actuated means whereby the" l y The Vfree end' 'fof the boom- 1s-` *designed to The 'hjectf `of my inventionk isfto provide` al i simple," "durable u and, inexpensive` device for elevating and` lovveringthe free *end- @of the boom, whereby theffree-endi of Will l be automatically supported `fagainst rapid downward movement f `in` f the 'eventfof disconnection orfailure of thepovver toelef boom may be easily and quickly manipulated to lock thefboorn in anyof' itsfelevated polsi; tions. I l' More specically it` is` thefobjefctfof'my invention, to :provide in` connection iwith a boom hoisting mechanism, including al rota-f tively n mounted cable `k'zlrumadapted4 tone operated4 in lonejdirection; yforn'hoisting ythe boom and operated in tlieuoppositedirection as the .'boomfis lI I`1ovedto lovveriposition of movement, means `actuated by. theS reverse movement of the cablehdrlim `for retarding the lowering-action" of the boom, Afvvhereby theboom may'` be lowered-atal comparatively slow speed andrby gravityL-alonqwithout thefuse of reverse power` mechanismg`and tof` provide vin connection :therewith means for v locking the fboom -against 4downward movement atpthe will ofthezoperatorfand When the looom is in any Tof Tits vertioal swinging positions oi movement.- f

. f My inventionlconsists in theconstructi-on, i

arrangement Aand combinationoithe various parts-ofthe device,vvhereby the objects con,

templated are attained, 'ashereinaftenniore fully set i`orth,`pointedl foutfin my claims, and 'illustrated in :the: accompanyingdraw?v -lllgylnWhlCh z l, if r Q gjrljfv; Figure 1 is a side'elevation of af'segniental portion of an excavating mechanism and 'a pivoted boom showing the mannerin? which myimproved locking mechanismwisiapplied thereto.' Figure 2 is a v`Iliave ansed the numeral 10i lto"` indicatell an excavatorfplatform offordinary construction and desigrledto-,be rotatively'mountedlabout a` 'verticali axisuon illustraeidr@ Thepla' `form 1 0 is provided-witha'boom 11 pivqtally monntedythereto bye pivot 12;

Igering-fin veaialfplahef Thefplatfofmlo erowtively mounted a' Sliaft 114V Sad @hm is rota-tively wmolmted infbe'aringmembers 15 andlly fOneend; offtheyshaft 14fhasa cable drum '17 `provided .with a lcable 18,

one end of which is" connected to"v saidf fdrnrn and the OppSte n'd'; passed, over" 21 Pulley 19 `carried byv the" free lend;ofjthe looomj'll,

friedby the-frameimembee; n Y 1 l this arangeme'ntj "vvillfbe seen `that rotation o'f the jdrumflf 'in one .direction Iwill cause "the free end,y of fthe; boom" 11 to,"` be elevated and that the weightof the vfree end of theboom will*` causethe drum tojbe a lriggirefcn is'a Vdetail sectional vievv taken l fan I excavator truck `not is" provided vWith r'amemembers' 13" in which y and then returned to aY fixed y"point "cadr a operated inthe opposite direction'rwhenthe v powerwfor rotatingA said diumvis discon-f j l ordinary bucket 21. J

neeted; The boomt; is' y provided f 4with y the on the oppositeendof the shaft lfllfaclutcli member, 22 permanently `keyed` to saidffshaft.

A coacting clutch drum 423 ivsmountedon sleeve 24, the inner endV ofyvhich isvconne'cte'd to la gear 25 includedin the ilSual train'gof ously infone direction;` :The clutch members; are closed and openedby `means offaylever device QZalso of ordinary construction.

. :By `this arrangement it will be seen-that f manipulating the coacting clutch *members t n A2 2 and 23,111@ ,shaft '.14 may, be 1rotated te" wind the cable 18 and to elevate the free end of the boom. A

For locking or retarding the downward i movement of the :tree end of the boom, I

inner end of the sleeve- 31is -.provided*with Y a worm gear 32 designed to coact with a worm 33V mounted on the upper end of a ver# tically arranged shaft34.`^ 'Said shaft 34is,` rotatively mounted in l'a Ihousing 35. `Thel lower end of the shaft 33"-is provided with a brake drum `36yhav`ing Libraire-,band 37 designedfto be operated by a leverrdevice 38 of ordinary construction. The lever 38 is controlled bya rod39 provided with suitable lever arrangement including means for locking the band 37 in a closed p0sitio'n.;r`

.By vthisvarran'gement it will be seen that as the shaft 14 is rotated in an anticlockwise direction, as viewedin Figure .1, the `cable 18 will be wound and the freeend ofgtheboom 11 elevated. Releasing the clutch-members 22` and 23 willstop the elevationlofthesaid boom andthe drum 17 willbe rotated `in a' reverse direction bythe'weight of ther said boom, causing the pavvl 2 9 toengage the ratchet teeth of the ratchet 30, which in turn will cause the sleeve 31 to be rotated, togethervwith the worm gear 3.2. Said gear 32 causes the worm 33 and the shaft 34 to be rotated. r The gear ratio ofthe said worm gear is such thatthe free `end of the boom will be permittedjto descend slowly.

The speed ratio of the worm gear and its coactingworm is. such that the weight of the boom 11 will cause ,the worm 33 to rotate at a comparatively slow speed` without locking the boom against downward' movef ment, which inactualpractice is somewhat 'less than 32 to V1,'as ratio` above 32 to 1 under ordinary operating conditions will automatically lock the boom againstl downward movement.

' I am well aware that worm gears have been providedfor driving-*the boomv elevating drum in both directions. The gear ratio is such that the boom is locked against downward movement whenpower is disconnected from theworm, and thereby providing means for automatically locking the boom against lowering.

I find in actriz-rlv practice, however, that this arrangement is objectionable in that the gear mechanism for driving the worm must operate at a high speed, which results in'considerable loss of power,'due to :triction, and furthermore, reverse mechanism must be provided for lowering l,the boom,

Y which adds considerable to the weight of the machine and to the expense.

In my improved hoisting mechanism the ordinary spur gear drive is provided for elevating the boom by rotating the cable drum in the usual manner. The loss of friction due to this arrangement is reduced substan# tially to a minimum. The lowering ci the boom` is automatically controlled by very simple and effective ratchet and worm gear arrangement, no power being required from the power` device. Means is provided in the drum36and the brake band 37 for locking the Y wormshaft 34 against rotation and the `boom against'lowering.

Onaccount ofthe high speed ratioV be-v i i tweenv thev worm and worm gear, it will bev seen that a comparatively small amount of power is required for locking the shaft 34, which results in a locking device which may be easily controlled by the operator.` Y l Whilemy improved hoisting mechanism is illustrated as beingl applied to elevatejandlower the free end of an excavatorboom, it will readily be seen thatthe same mechanism might `be applied to any,A e, cable drum `in which the .weight is suspended directly from f the cablewound thereon.,n .Y

I Furthermore, the clutchmechanism illustrated, is hand controlled, while it willjreadily be seenthat a mechanically 'controlled clutch device might be substituted such as in common useon :excavating mechanism.v n

Thus it will be seen that I have provided a. hoisting .mechanism of simple, durable andr einexpensive construction, in which a minimum j lamount of jpowery is, required for operating" the hoisting drum, and in which the excessive downwardfmovement of the Weight', carriedA bythe drum cable is automatically controlled, and iinwhich all power forthe operation ofthe device, as the weight isvbeinglowered, islimited.

I claimas my invention: 1.,.In combination, a cable drum, a clutch controlled mechanism forgimparting windingl movement to said drum, a worm gear mechanism for' retardin'g" the unwinding movement of said drum, means actuated by the reverse movement of said drum forl automatically V,connecting saidworm gear mechanism to said drum. e

2. In combination, acable drum, a clutch controlled,` mechanism for imparting winding movement' to said drum, afworm gear mechanism for retardingv the unwinding movement of .said drum, means actuated by the reversemovementof said drum for automatically'connecting said worm gear mechanism to said drum, a brake drum operatively connecting the 'driven member of said worm gearmechanism, and hand controlled brake band for said drum.l s

' 3.In combination, a cable drum, a driving gear, a clutch for operatively connecting said gearlandl said drum,'worm gear speed retarding mechanism, a ratchetdevice for oper- Y clutch for operatively connecting said gear and said drum, Worm gear speed reducing atively `connecting said worm gear mechanism to said drum upon reverse movement of said drum.

4. In combination, a cable drum, a cable connected to said drum, a driving gear, a

mechanism, means for operatively connect'- ing said worm gear mechanism to said drum upon reverse movement of said drum, the. speed ratio of said worm gears being such that the drum will be unwound at a comparatively low speed and by Weight applied Y Y Y to said cable.

GEORGE T. RoNK. 

